Thank you Gildor

Just to clarify a couple of things:

The blending in the overland map you see above is achieved by using CC3's sheet effects. These are roughly equivalent to GIMP Filters or Photoshop Layer effects, but I didn't understand them well enough to use them proficiently for a couple of months when I first started drawing CC3 maps. First maps in CC3 tend to look a lot less blended - a bit more 'stamped in', as you say, but at least you can see from my example that it doesn't have to look that way.

CC3 is a vector programme. When I use GIMP to modify a CC3 map, I export a simple JPG or PNG file from CC3, which I then open in GIMP as a single layer image. Its possible to export separate sheets from CC3 and recombine them in GIMP as separate layers, but the transition from CC3 sheets to GIMP layers is quite a time consuming exercise.

If you do decide to go down the road of choosing CC3, There are quite a few of us here who can help you learn the way after you've done the example in the manual, and there's an even bigger reservoir of skill and experience of CC3 over at the Profantasy Forum.